Waldo Township is located in Livingston County, Illinois. As of the 2010 census, its population was 255 and it contained 100 housing units.
On September 12, 1860, the area comprising Waldo Township was split from Nebraska Township and established as Kansas Township. Some time later, the name was changed to Waldo Township as there are Kansas-named townships in Edgar and Woodford counties.
According to the 2010 census, the township has a total area of , all land.